Clinical Implications of Preformed Archwire Selection on the Treatment of Angle Class I/II division 1 Malocclusions in Thais.

INTRODUCTION: The dental arch forms were compared of untreated Class I and Class II div 1 malocclusions to those of non-customized preformed archwires manufactured by American Orthodontics, G&H, Highland, Ormco, RMO, and 3MUnitek. Arch forms of post-treatment Class II div 1 malocclusions treated by four 1st premolar extractions are also compared. MATERIALS AND METHODS: Four metrics of archform shape and size (canine and 1(st) molar depth and inter-canine and inter 1(st) molar width) were measured on dental casts of 40 Class I and 22 Class II div 1 patients. These same metrics were also used to describe preformed archwire forms. RESULTS: Non-customized preformed wires all showed significantly narrowed mandibular arch forms. This was true for maxillary archwires, with four exceptions. The Highland Natural Arch form, G&H True form I, and RMO natural preformed archwires showed both inter-canine and 1(st) molar widths statistically the same as mean dental arch widths in both the untreated and post-treatment Class II groups. In Class I patients, these three archwires showed only inter-canine widths equivalent to dental measurements. The Highland Progressive archwire matched only the 1(st) molar width in the untreated Class II group. CONCLUSION: None of these archwires - if used unadjusted, will produce a significant expansive force in either the maxillary or mandibular arch. Three maxillary non-customized preformed archwires showed both inter-canine and 1(st) molar arch widths statistically the same as Thai Class II div 1 dental arch dimensions. Using them to treat this malocclusion should minimally affect both pre and post-treatment maxillary arch form.

National Institute of Dental and Craniofacial Research efficacy trials of bionator class II treatment: a review.

Reviewing publications from two North American functional appliance efficacy trials on Class II/1 malocclusions, we conclude that preadolescents show first molar correction in 13% of untreated cases, 38% of bionator-treated cases, and 50% of combined headgear/biteplane-treated cases. Also, bionator and headgear reduce ANB differences at nearly equivalent rates (degrees/year). Thirty-two percent of untreated patients show favorable reductions (>0.5 degrees/y), compared with 80% of patients treated by either bionators or headgear. Successful outcomes, however, are highly dependent on the severity of the malocclusion. Using either headgear or bionators, clinicians should expect successful Class II molar correction in over 57% of preadolescents presenting with half cusp molar discrepancies. When left untreated, 30% of such patients are reported to attain a Class 1 molar relation. But only 5% of cases presenting with greater than half cusp discrepancies are found to resolve themselves. The bionator appliance, though, corrects 30% of such cases, and combined headgear/biteplane treatment corrects 40%.